Tu Illuminatio Mea

Summary:

When Sherlock announces the arrival of a friend, John's more surprised that Sherlock has friends than anything else. But then he meets Rachel.

Notes:

Written for DW's Sherlock_Flashfic's "The Case of the Oxford [ _____ ]." Rachel really did make a drink called "The Invisible Ink" after her series of "Moment of Geek" re: the recently-declassified CIA documents on the subject. Title is a bastardization of Oxford University's motto, "Dominus Illuminatio Mea" ("God is my Light").

Work Text:

"There will be a guest staying with us this weekend."

John stopped typing, fingers still poised over his laptop, and glanced over at Sherlock. His flatmate was sitting on the far end of the sitting room on the sofa, lying on his back in his dressing gown with his fingers steepled to his lips while he stared up at the ceiling, in such great concentration that it was almost as if he hadn't spoken in the same tone he would have used to announce that he was taking up yoga or that Mrs. Hudson had discovered a dead body buried in her back garden.

Nevertheless, John thought it safer to confirm that he hadn't just hallucinated Sherlock saying things. "Were you asking me, or telling me?"

"Did it sound like a question to you?" Sherlock rolled over onto his side so that his concentrated stare was now focused at John. "An American friend of mine emailed me this morning to say that she will be arriving in London tomorrow on a one-night stopover from Paris. I thought it would be easier for her to stay with us, rather than trying to find a hotel on a moment's notice."

You have friends? John wanted to ask, but instead he said, "She? Are you sure she'll be willing to stay in a small flat with two men? I'm sure there are plenty of rooms available elsewhe—"

"She was perfectly willing when I offered," Sherlock interrupted. "And don't worry about her delicate sensibilities, John. I daresay her sensibilities have not changed much since our Oxford days, and at that time she never much minded the state of my flat when she came to visit."

"Heavens, no. She came on a Rhodes scholarship to pursue her doctoral thesis shortly after I enrolled. In any case, she's a lesbian, so I'm sure she won't be interested in molesting either of us in our sleep, if that's what you're worried about." Sherlock got to his feet and strolled languidly out of the sitting room towards his own room. "If you can get out of clinic early tomorrow, Rachel should be here in time for tea," Sherlock called from the hallway. "Otherwise, I've already reserved dinner for the three of us at Angelo's."

"Does this Rachel have a last name?" John asked, but Sherlock had already gone into his bedroom and slammed the door behind him.

John sighed, minimised the Notepad window for his latest blog entry, and opened up a new email window instead. Hey Sarah, I know I said we could go out tomorrow, but something's come up...

* *

John did get out early from clinic the next afternoon, but Sherlock wasn't home. There was, however, another tall, skinny, boyish figure sitting in Sherlock's usual seat on the sofa with his (or her?) back to the doorway.

"Hullo, sorry, hope you've not been waiting long," John began, and then he stopped in his tracks when the figure turned around.

"He has?" John moved past Rachel and into the kitchen to start preparing tea. "You know him well, then?"

"As well as anyone knows Sherlock, I suppose." Rachel sounded fondly reminiscent. "We met at Oxford, I don't know if he told you—I was hardly off the plane from the States when they had me attend the welcome banquet for the Rhodes Scholars, and they kept pointing me out as the first openly gay Scholar all the damn time. I didn't like it at all at first; but then I met Sherlock when I went to hide at the champagne table, and I started making the drinks while he told me which person wanted what and why, just by looking at them." Rachel laughed again. "He wasn't exactly tactful, most of the time, but he was scarily accurate, and it kept me from feeling awkward for the rest of the night. And here I am."

"Sounds like Sherlock hasn't changed a bit, then." The kettle whistled loudly, and John busied himself with the two last clean mugs in the flat (stored as far away from Sherlock's newest experiments with growing fungus in the kitchen sink as possible) before bringing the steaming teapot and mugs on a tray into the sitting room. "I'm sorry the place is such a mess, but most of it's Sherlock's and I hadn't the time to ask him to clean it up before you came. Sugar or milk with your tea?"

"Just plain tea for me, thanks." Rachel accepted her mug and blew on the hot liquid, glancing around the room as she did so. "Actually, I was going to congratulate you on getting Sherlock to pick up after himself better. You should have seen his rooms back in college—it was worse than if someone had detonated a landmine. I could never get from one side to the other without stepping in something that used to be alive, or still was."

John was about to commiserate with Rachel's experiences, given that he'd spent the morning clearing frozen frog sperm out of the refrigerator, when his phone buzzed with an incoming text.

John hesitated. A new case? Would Rachel really want to tag along while Sherlock puttered and John watched from the sidelines? Shouldn't John at least give her some time to rest after her flight instead?

While he hesitated, a third text popped up on his phone's screen.

Trust me. If you won't, at least ask her if she's interested.
SH

John cleared his throat and looked up at Rachel. "Um. Seems like Sherlock's tied up with a case at the moment. He thought you might want to come, but you're more than welcome to make yourself at home and take a nap before dinn—"

"Are you joking? A real case? I'd never miss it." Rachel's eyes sparkled as she set down her mug and got to her feet. "Lead the way, good sir."

Before he locked the door of the flat on the way out, John sent Sherlock a text in response.

I will never understand how you know these things, damn you.

Don't feel too bad. Not many do.
SH

* *

Their arrival at Scotland Yard garnered John some odd looks, not least because Rachel's crisp American accent cut through the usual conversation of British dialect as they chatted on their way to Lestrade's office. It seemed that some of the officers recognized Rachel as well, as John caught a glimpse of several cameraphones surreptitiously flashing at them while he led Rachel in a maze-like path between desks.

Word of their arrival traveled fast, as Lestrade was already waiting for them outside his office. "Sorry, John," Lestrade said, nodding at Rachel, "but if she's from the press, I can't have her come in. Open investigation, rules to be followed and all that. God knows I've bent enough of them to have you and Sherlock assist—"

"But I'm not press!" Rachel protested. "Well. I am, but not right now."

"And in any case, none of that matters because I invited her." Sherlock pushed past Lestrade and out into the hallway. "Dr. Maddow, how wonderful of you to join us."

"Sherlock!" Rachel bounded forward and flung her arms around Sherlock, thumping him on the back in a manly embrace, and—was John seeing things?—Sherlock hugged, yes, hugged her back just as tightly. "It's so good to see you!"

"Likewise." When they broke apart, Sherlock was truly smiling, the happiest he'd looked since solving the last serial murder case two weeks ago. "I see Susan's latest project is going well."

"You see rightly!" Rachel's loud peals of laughter made several officers look up from their desks again. "Did you get that from looking at me just now, or were you Googling Susan's website before I got here?"

"Rachel, you wound me. If you must know, it was your watch and your right-hand shirt cuff that gave it away. Also, there is the fact that you came from Paris, which I assume is after you went with Susan to open her gallery exhibit." Sherlock turned to Lestrade, whose stunned expression must have complemented the look on John's face. "Rachel, this is Inspector Lestrade. Inspector, this is Dr. Rachel Maddow, a colleague of mine from Oxford."

"Hi!" Rachel said brightly. Lestrade shook the hand she offered, still looking rather bemused as Sherlock pulled Rachel behind him into Lestrade's now-empty office.

"Did you know he could be so—human?" Lestrade asked John. "Is this a recent development?"

"Dunno. I just met her an hour ago." John shrugged. "I think it's just limited to her, though. Anyway. Sherlock said you had a new case?"

"Not in the strictest sense, no." Lestrade guided John into the office, ignoring Sherlock and Rachel already poring over a pile of evidence inventory on one corner of the desk, and dropped a medical file folder into John's waiting hands. "Jeremiah Lovelace, age sixty-seven, lived alone in a cheap walk-up in Islington for the past thirty-odd years, until his landlady found him dead yesterday morning. Autopsy says he suffered a heart attack, cardiac arrest, time of death around eight to ten hours before he was found. Toxicology was clean, and no sign of trauma or any injuries suggesting foul play."

John looked up from examining the crime scene photo of the body, which was slumped in its chair behind a rolltop desk, surprised. "Then what are we here for?"

"Because the evidence doesn't match the crime," Sherlock put in from his corner. "We know Mr. Lovelace worked for the Russian Mafia, since at least the eighties if the design of the tattoos on his left wrist is anything to go by, and he only retired very recently. He still wore his ankle holster, but the gun it held was found in his desk drawer. If he still worked for them—"

"He would still have the gun on his ankle, I got it the first time," Lestrade snapped. "But you can't make the crime fit the evidence, Sherlock! I don't care if you think the Mafia whacked him, there's no sign of foul play at all!"

"Then what's this?" Sherlock waved an evidence baggie containing a single piece of paper before passing it to Rachel, who in turn handed it to John for him to see. The paper was mostly blank, with blocky letters of single-word text spread out unevenly in the middle of the page.

STOLE
FROM

SISTER

SORRY

"Sounds like a suicide note to me," John said after a moment. "He stole something from his sister, and he's sorry?"

"But it wasn't a suicide," Sherlock corrected. "Toxicology came back clean, didn't you say, Inspector?"

"Maybe he knew he was dying and was confessing his sins before it was too late?" John offered. "Does he even have a sister?"

"Yes, she's the next-of-kin, but we haven't been able to reach her. She's on vacation in the country until next week," Lestrade said. "And until we do, this case is closed, Sherlock."

Lestrade's tone brooked no argument, but Sherlock nevertheless sniffed in disdain. "Fine. But I'm taking that paper with me. If I can't decode or decipher it by the end of the night, I promise I'll buy the whole shift dinner."

Rachel and John's eyes met just before Lestrade huffed his agreement, and Rachel grinned. Hasn't changed, she mouthed silently at John, and John barely managed to turn his snort of suppressed laughter into a fake cough.

* *

John ended up canceling their dinner reservation at Angelo's, as Sherlock was too busy sulking and staring holes into the wall with the power of his mind (i.e., he was "thinking") to eat properly. They did Indian takeaway at the flat instead, with enough naan and basmati rice to feed five hungry men, and Rachel and John kept up a steady stream of conversation on a wide topic of current events while Sherlock remained silent and picked at his food morosely.

John was in the middle of explaining to Rachel what he really thought of Afghanistan ("Believe me, if Blair or Brown or even Cameron were shoved into the middle of a firefight with only a flak jacket and a helmet like what I had, our men would be out of there faster than you could say 'Islamabad.'"

"I don't know, I can say 'Islamabad' pretty fast...") when Sherlock suddenly growled and slammed his open hand on the table, rattling the silverware dangerously. "Dammit!" he spat. "I've tried every single code known to man, every substitution cipher, even tried them all backwards—nothing!"

"Maybe you're looking for the wrong thing," John tried, consolingly. "Maybe there's nothing else there, it could just be—"

"I'm telling you, John, something isn't right! The spaces between the words make no sense, nor does the message itself! If he was writing it to his sister, he would never have worded it that way!" Sherlock paused. "Maybe the spaces themselves are code. The ratio of blank space to the number of letters, yes, perhaps..."

"Well, that's it." Rachel got to her feet and stretched. "I know what would help us all think—a good drink. Sherlock, where do you keep the alcohol around here?"

John had opened his mouth to apologise for the serious dearth of liquor in their flat, when to his great surprise Sherlock snapped out of his thoughts long enough to say, "Kitchen, last cupboard on the left, behind the empty beakers."

John stared at his flatmate as Rachel disappeared behind the door of the full-length pantry cabinet. "You said you didn't drink!" John accused, feeling more than a little betrayed. "And that we didn't have any—"

"Believe me, John, you wouldn't have done much good with what I have." Sherlock's lips quirked. "These are all specialty liquors and spirits. I would trust Rachel alone with my cocktail, and you should do the same. Once you have one of her creations, you would swear off all other alcohol as well."

"I'm touched!" Rachel shouted from the sink. "But that's an awfully long time to go without alcohol!"

Sherlock shrugged. "I don't like what alcohol does to impair the mind, that's true," he allowed. "But Rachel doesn't make cocktails—"

"—I make drinks," Rachel finished, walking back into the dining area with two cocktail glasses (John didn't even know they had those) that she set in front of John and Sherlock. "And a drink is meant to be imbibed and enjoyed. Go on, drink up!"

John picked up his glass and swirled it. "What is this?" he asked.

Rachel grinned playfully. "I'll tell you once you've tried it."

John looked over at Sherlock, who had already taken a sip, and Sherlock gave him an encouraging nod. John closed his eyes, put the glass to his lips—

—and tasted the most heavenly mouthful of alcohol he'd ever had in his life.

"Wow," John managed, about two seconds later than he probably should have. "That—that's excellent."

Rachel beamed. Sherlock, on the other hand, sniffed his glass. "What did you use?"

"Well, I noticed you still had a little Cynar left, so I mixed that with a regular gin-and-tonic, and lime. A lot of lime," Rachel added, with a laugh. "I covered this on my show a few weeks ago, but Cynar is made from asparagus juice, which apparently can be used as a kind of invisible ink. CIA released some classified docs from the last World War, it's on my website—but anyway, that's why I call this "The Invisible Ink." Catchy, huh?"

Sherlock suddenly stilled. "Say that again."

"What? Uh, I noticed you still had a little Cyn—"

"No, no, the invisible ink, invisible ink!" Sherlock jumped up and started to pace. "Why didn't I see that before? Of course, it's a secret message!"

"The empty spaces, then—that's where the rest of the message is?" John asked, starting to catch on.

"Oh my God, that's it!" Rachel clapped her hands together. "We need an iron. That should reveal the ink. Do you have an iron?"

"No, but Mrs. Hudson does," Sherlock said before dashing out of the room.

"Be sure to ask nicely!" John shouted after him, but Sherlock was already long gone.

"He's brilliant." Rachel sighed happily. "Isn't he?"

"Brilliant, yes." John rubbed his temples. "Unmanageable, also yes. As impatient and annoying as a bloody three-year-old, that, too."

Rachel laughed. "But that's why we love him," she said, so gently that John almost missed what she'd said.

John didn't have a chance to reply, as Sherlock chose that moment to stride back into the flat, armed with Mrs. Hudson's iron. "She wasn't there," Sherlock announced. "And don't look at me like that, John, her door was unlocked. She won't even notice that it's gone. Rachel, where's the paper?"

"Right here!" Rachel handed the evidence baggie over to Sherlock, who ripped open the seal without ceremony (Anderson is going to have kittens, thought John) and flattened out the paper on the dining room table before pressing the steaming iron on top of it.

"What does it say?" Rachel asked, eagerly peering over Sherlock's shoulder as the paper smoked. John got up from his seat and leaned over, the better to read the faint greenish-white letters that had appeared in the spaces around and between the regularly-inked words that were there before.

GIVEBACKWHATYOUSTOLEFROMUSORYOURSISTERWILLBESORRY

"Oh," said Sherlock softly. "Oh. This changes everything."

* *

"Let me get this straight," John said the next morning, as the three of them waited at Heathrow for Rachel's plane to board (how Sherlock had managed to get all three of them past security without a proper boarding pass, John would never know, though he suspected it had something to do with Mycroft). "So, Lovelace used to work for the Russian Mafia, and then he retired and—took an extra retirement pension with him when he left?"

"Precisely." Sherlock rocked back and forth in his seat, looking very pleased. "Lovelace was very good at bookkeeping, and he proved it by laundering at least a hundred thousand pounds from the Mafia accounts into his own personal savings. Not even Mycroft saw it until I asked him to look specifically at the transaction details. And I assume that Mr. Lovelace's bosses were not best pleased when they found out, either."

"So they took his sister hostage?"

"Apparently, yes. They kidnapped her just after she arrived in Sheffield for a quiet vacation there. The police found her early this morning, alive and relatively well, and they even managed to book her captors." Sherlock drummed his fingers on his leather armrest. "She was a retired schoolteacher, lived alone like her brother, had a few cats, but that was all. No doubt finding out that her brother worked for the Mafia must have been a bit of a shock."

"Which leaves this Jeremiah Lovelace," Rachel broke in. "How did he end up dead, anyway? Was it murder?"

"No. Mr. Lovelace had a genetic predisposition for a weak heart to begin with, and clearly the stress from hiding all of his secrets was taking its toll on his health. The ransom note was just the final straw that broke the camel's back—or, in this case, Mr. Lovelace's heart."

"And the reason why the police didn't see the full note was because it had already cooled down by the time they arrived," John finished. "Well. Good to know you won't have to buy the whole team dinner, Sherlock. Donovan would have never let you live that down."

Rachel leaned closer to John as Sherlock stalked towards the unsuspecting ladies at the check-in counter. "You've done him good, you know," she said with a small smile. "He's happier, now. When I last saw him a few years back, he was so bored that half the time he couldn't even see straight. But now, with you—he's something else."

"Yeah, when Sherlock gets bored, you need to find the nearest bunker and hide." John scratched his neck awkwardly. "I was thinking the same thing about you, actually," he admitted. "When Sherlock's with you, I've never seen him so, I don't know—"

"Relaxed? Yeah, I know what you mean." Rachel quirked a grin. "He doesn't really feel threatened by me, you see. I'd never be interested in him in any other way than as a friend, and he knows it. Sherlock's one fault is that he's easily frightened by emotions he can't understand at an intellectual level, and he tries to push their sources as far away as he can. Hate and grief, he can understand, and he embraces that in his mysteries. But love and caring? That confuses him, makes him uncomfortable, and sometimes he doesn't know how to cope."

Rachel took John's hand and squeezed it tightly. "Trust me on this one," she said, and winked. "If he's ever a little more obnoxious to you than usual, just think about that, OK? He really does need you, even if he doesn't know it yet. But he'll see. He'll see."

"Dr. Maddow, your plane awaits." Sherlock appeared, a dark shadow blocking out the sun directly in front of them, and handed a new boarding pass to Rachel. "Here's your ticket."

"But I've already got—" Rachel stared at the new pass. "Sherlock, this is for first class."

"Precisely. Which means, I believe, your boarding time begins now." Sherlock stuffed his hands in his pockets, and for a moment John could see the discomfiture that Rachel had just been describing. "Consider this a parting gift."

"Oh, Sherlock." Rachel stood and hugged Sherlock; and for the second time in as many days, John couldn't help but stare at the two of them. "I'll miss you. You should come visit me in New York sometime." Rachel pulled back and nodded at John. "You, too. I'd love to have both of you over, and I'm sure Susan would be delighted to meet you guys."

"I will consider it." Sherlock's smile this time was a more wistful expression. "You know how international flights bore me so."

"Well, if it's any consolation, I promise I'll make you as many drinks as you want if you do—oh, that reminds me! I almost forgot!" Rachel rummaged in her jacket pocket for a moment before fishing out a crumpled cocktail napkin and giving it to John. "For your sister," she said, and with one last farewell wave, Rachel took off running for the gate.

John waited until Rachel had completely disappeared in the depths of the aerobridge before straightening out the cocktail napkin in his hands. There, printed in neat broad strokes with an ink pen, was a short message.

To Harry Watson:
Don't eat the garnish!
With love from RACHEL MADDOW

"That's a favorite saying of hers." John glanced up to find Sherlock standing even closer to him than before, apparently so that he could read Rachel's napkin upside down. "She is very fussy about people eating the fruit decorations on her drinks, as I learned the hard way around ten years ago. She stopped speaking to me for five days."

"I see." John leaned back so that he could see Sherlock's face better. "Are you going to take her up on her offer, then? To visit her, I mean."

"Perhaps." Sherlock turned, and John suddenly felt himself on the receiving end of Sherlock's unbridled intense stare. "She invited you, as well. What do you think?"

John pondered the question for a long moment. "Well, I've heard New York's crime rate is pretty high no matter what time of year," he finally said, and Sherlock's surprised and delighted laugh was enough to lodge a warm glow of pleasure deep in the base of John's abdomen that didn't go away for quite a while after.

And then they went home and ended up walking in on an ongoing surprise drugs bust led by none other than a seething Anderson, but that was just par for the course, really.